Window units for oven doors conventionally have consisted of constructions in which the space between the glass panes is sealed to prevent oven vapors from penetrating that space and subsequently condensing on the glass surfaces. Such constructions result in the outer surface of the outer glass reaching fairly high temperatures. Various attempts have been made to reduce the temperature of the outer glass by providing for the flow of air by convection over the inner surface of the outer glass but such proposals have frequently involved constructions that require the use of three panes of glass or that could not utilize a self-contained window unit adapted for easy installation into the oven doors of the various oven manufacturers. The present invention provides such a self-contained unit having the advantages of cooling the outer glass by an air flow over its inner surface and providing for the easy removal and replacement of the glass for cleaning purposes.